Icon Technical Definition
Octet-gram of cloud cover, blue is for clear while white is for cloud. e.g. the "cake" on the left is 0% cloud while the one on the right is 100% cloud.
Astronomical seeing. From left to right: <0.5", 0.5"-0.75", 0.75"-1", 1"-1.25", 1.25"-1.5", 1.5"-2", 2"-2.5", >2.5". In short, the smaller/bluer, the better the seeing condition is.
Atmospheric transparency. From left to right: <0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.85, 0.85-1, >1 (unit: mag per air mass). In short, the fewer bars/bluer, the better the transparency is.
Chances of rain/snow.
Atmospheric instability. From left to right: lifted index between 0 to -3, -3 to -5, and below -5.
Humid weather warning. From left to right: relative humidity between 80%-90%, 90%-95%, and over 95%.
Windy weather warning. From left to right: sustained wind speed between 8.0-10.8m/s (fresh), 10.8-17.2m/s (strong), and over 17.2m/s (gale or above).